[Study of eggshell performance as a natural sorbent for the removal of reactive red 198 dye from aqueous solution]

Dye compounds is one of the most critical contaminant for natural ecosystems. The aim of this study were to determine the primary concentrations of reactive red 198 dye [RR 198], adsorbent dosage and pH influences for the adsorption of RR 198 onto chicken's eggshell [ES] as an adsorbent. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Surface characteristics and measurement of the adsorbent surface area was carried out with Scanning electronic microscope [SEM] and via N2 gas adsorption with Brunauer-Emmett-Teller isotherm. The maximum absorption wave length of this dye [lamda-max] was determined by spectrophotometer [Optima SP-3000 Plus]. Analysis of absorption spectra showed that the lamda-max of RR198 is 518 nm. The results show the Calcium components are the main constituent of ES with 1.2 m[2]/g. Elevation of the ES dose [2 to3 g] lead to increasing of dye removal from 80% to 92%. The results show that elevation of pH from 4 to 10 would lead to increasing of RR 198 adsorption from 44% to 64% but increasing of preliminary dye concentration would lead to decreasing of dye adsorption from 72% to 23%. The kinetic studies revealed that the adsorption of RR 198 is rapid and complying with second-order kinetic [R2=0.995] which the kinetic constant is 0.0004min-1. Eggshell is a cheap adsorbent that can be used for the removal of dye components from alkaline solutions

Equilibrium and kinetics study of reactive red 123 dye removal from aqueous solution by adsorption on eggshell

The aim of this study was to determine the equilibrium and kinetics adsorption of reactive red 123 dye [RR 123] from aqueous solution with chicken's eggshell as an adsorbent. The initial concentrations of reactive red 123 dye were selected in the range of 25 and 50 mg/L. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Measurement of the adsorbent surface area was carried out via Brunauer Emmett-Teller isotherm. The experimental data were analyzed with Langmuir, Freundlich and Temkin isotherm models. The results showed that the calcium components were the main constituents of eggshell [around 95% Ca]. The experimental adsorption isotherm was in good concordance with Langmuir and Freundlich models [R[2]>0.90] and based on the Langmuir isotherm the maximum amount of adsorption [q[max]] was 1.26 mg/g. Increase of the eggshell dose and the solution temperature beyond 45 Degree C led to decrease of the adsorbed dye per mass unit of the adsorbent, but increase of the solution pH up to 9 led to the improvement of dye adsorption. The kinetic studies revealed that the adsorption of reactive red 123 was rapid and complied with pseudo-second order kinetic [R[2]= 0.99], with the kinetic constant of 0.02 g/mg.min

[Application of solar irradiation / K2S2O8 photochemical oxidation process for the removal of reactive blue 19 dye from aqueous solutions]

Dyes are organic compounds with complex structures, which due to toxicity, carcinogenicity and nonbiodegradabity, this type of pollutants is one of the most important pollutants of the environment. The goal of this research was to study the feasibility of the application of solar irradiation in presence of potassium persulfate [K[2]S[2]O8] for the removal of Reactive blue19 [RB19] from synthetic wastewater. This research was carried out in laboratory scale with using of 200ml volume of batch photoreactor. The effects of operating parameters such as concentration of K[2]S[2]O[8], pH, photo exposure time and preliminary concentrations of dye on decolonization have been evaluated. Different concentrations of pollutant in waste water were prepared by solution of variousmasses of RB19 on tap water. The reactors were exposed with natural solar irradiation as a UVA source from11 am to 14 pm. The maximum absorption wave length of this dye [lambda[max]] was determined by spectrophotometer [Unico, 2100]. The measurement of dye concentrations was determined with using of standard curve and its best line equation Analysis of absorbtion spectra showed that the lambda[max] of RB19 is 592 nm. The average intensity of the UVA irradiated from solar system was 54.6 microW/Cm2. The results of decolorization process showed that 38.2%of this dye can be removed within 3 hr in the presence of potassium persulfate and decreasing of pH leads to the elevation of dye removal efficiency. Based on these findings, the efficiency of dye removal with 3h photo exposure time and pH ranges of 4,6 and 8 were found to be 98.2 88.5 and 78.5%, respectively. Also, the results showed that increasing of K[2]S[2]O[8] dosage leads to elevation of dye removal efficiency in 3h photo exposure time and K[2]S[2]O[8] dosages within 1-5mmol/L, with the removal efficiency of 75,86,92,95 and 98.5%, respectively. Analysis of data indicates that the kinetic of the removal of RB19 with this process is a first order reaction which its rate constant is 0.01min-1. Due to the operation problems presented in heterogeneous photocatalitical processes such as catalysts separation and high costs of operation and maintenance of these processes caused by manmade sources of irradiations; homogeneous photocatalitical process with using of potassium persulfate associated with natural solar irradiation can be used as a suitable process for the removal of dyes from textile industries wastewaters

Application of iron impregnated activated carbon for removal of arsenic from water

The presence of arsenic in drinking water is one of the greatest threats to public health. The aim of this experimental investigation was to study the removal efficiency of As [v] from water by application of iron-impregnated activated carbon [Fe-AC]. Coating of activated carbon with iron salt was carried out by impregnation method and thermo-chemical reactions with using of 100 mM FeCl3 solution. The Fe-AC was pulverized using ASTM standard sieves with the range of 16-20 mesh. The solid structure and surface characteristics of Fe-AC were determined using conventional techniques. Batch adsorption experiments were carried out with 300 and 600 micro Lig/L arsenate. Langmuir, Freundlich and Dubinin-Radushkevich models were used to describe the isotherm and energy of adsorption. The results of this study showed that 2.5 h contact time was enough to achieve the equilibrium. The adsorption of As [v] had a good compliance with Langmuir model [R[2]= 0.995] and the maximum adsorption capacity was obtained as 0.024 mg/g. The results of kinetic studies showed that As[v] adsorption on Fe-AC may be limited by film diffusion step [m=0.26]. The mean free energy of adsorption [E] calculated from Dubinin-Radushkevich isotherm was found to be 1.52 kj/mol which implies that the adsorption of As[v] on Fe-AC is a physical adsorption. The results indicated that Fe-AC is one of the suitable adsorbents which can be used for the treatment of arsenic contaminated waters

[Application of enzymatic polymerization process for the removal of phenol from synthetic wastewater]

Phenolic compounds are presence in many industrial wastewaters, and have been classified as priority pollutants. Application of several conventional processes due to high cost and low efficiency has been limited. Thus, new methods such as enzymatic polymerization seem to be preferable and effective processes with high potential to substitute the conventional processes. This study was carried out to evaluate Raphanus sativus extract as a peroxides enzyme source for polymerization and removal of phenol from synthetic wastewater in the presence of hydrogen peroxide. The study was performed in batch reactor at room temperature. Peroxidase enzyme was extracted from Raphanus sativus plant roots. Primary concentration of phenol in wastewater was 1000 mgl[-1]. The concentration of phenol and enzymatic activity was been measured by photometric assay. The results show that Raphanus sativus extract is a suitable source of peroxidase enzyme. Mean enzymatic activities in this extract was 3.107 Uml[-1]. Also, our results showed that elevation of extract volume lead to high efficiency of phenol removal, in which the increase in the extract volume from 5 to 50 ml, resulted in the efficiency of processes increased from 7.6 to 98.2%. Also, sequencing addition of H2O2 and extract has improved the effects. The phenol removal efficiency of the reaction time after 3 h with single and three stages adding of reactants was 84.2 and 93.1%, respectively. Enzymatic polymerization can be used as an appropriate process for the removal of phenolic compounds from wastewaters. To meet the optimized condition in process, the ratios of phenol/ enzyme and H2O2/ phenol and sequences of the adding of reactants should be considered

[Removal of methylene blue dye from synthetic wastewater with bone char]

Dyes are organic materials with complex structures, toxic, carcinogenic, teratogenic, nonbiodegredable properties and the most important pollutants of textile industrial wastewaters. The goal of this study was to survey the feasibility application of bone char [BC] as a sorbent for the removal of methylene blue [MB] from synthetic wastewater. The sub goals of the research were to determine the adsorption isotherm, effects of primary concentration of dye, adsorbent dose, contact time, and pH for the adsorption of MB with BC. BC was prepared under laboratory conditions by using of electrical furnace at 400°C for 2h. The prepared BC was crushed and pulverized by standard ASTM sieves with range of 10-16 mesh [1.18-2 mm]. The chemical composition and solid structure of BC was analyzed using X-ray diffraction [XRD] and scanning electronic microscopy [SEM]. Measurement of the surface area was carried out by N2 gas via BET isotherm and Belsorb software. The concentration of dye was measured by photometric method [663nm]. Predominant composition of BC is calcium hydroxyl apatite [Ca5 [PO4]3OH with 14m2/g surface area. The results of this study showed that increasing of primary concentration of dye, adsorbent dose and pH [5 to12] would lead to increasing of adsorption/removal of MB dye. Equilibration of dye adsorption was reached at lapse of 2h and optimum pH for adsorption of MB with BC found in the rage of 8.5-12. Adsorption of MB with BC complies with freundlich isotherm [R2: 0.99]. Conclusion: Bone char is a cheap component that can be used as an adsorbent in water and wastewater treatment. Based on optimum pH of 8.5-12 found for the removal of MB and the fact that many of textile industrial wastewaters have an alkaline pH, this adsorbent can be used for the removal of dyes from these wastewaters

Survey of corrosion and precipitation potential in dual water distribution system in kharanagh district of yazd province

Corrosion and precipitation in drinking and sanitary water in distribution systems leads to economic and health damages. The goal of this study was to survey the chemical quality of water in Kharanagh ward in Yazd province and to predict the potential of corrosion and precipitation in these waters. For determining the chemical quality of water, some cross-sectional samples with 2-4L of water volume were taken. All of the samples were collected, stored and preserved in glass or polyethylene containers and were analyzed based on standard methods. The potential of corrosion and precipitation in waters was calculated by Langelier Saturation Index [LSI], Risnar Index [RI] and decision was made based on calcium carbonate resistance. Based on the values of LSI, drinking and sanitary waters showed precipitative properties. Based on RI, the waters showed a corrosive quality from the point of corrosion and precipitation potential. Based on calcium carbonate resistance parameter, the waters had precipitative quality. The chemical quality of water in Kharanagh district is non-balanced that leads to precipitation in water distribution and other equipments thus planning water quality stabilization for the elimination of economics damages is necessary